JP2004190195A - Short fiber nonwoven fabric formed with molten lump and method for producing the same - Google Patents
Short fiber nonwoven fabric formed with molten lump and method for producing the same Download PDFInfo
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、護岸、軟弱地盤や廃棄物最終処理場等の様に長期間屋外に曝される環境で吸出し防止シート、不等沈下防止シート、保護シート等として用いられる短繊維不織布とその製造方法に関するものである。
【０００２】
【従来の技術】
従来から土木現場においては軟弱地盤における不等沈下防止や河川・海岸における洗屈防止・吸出し防止等を目的として土木現場においては各種不織布が土木シートとして用いられている。
【０００３】
これらの用途に用いる不織布は屋外で使用されることから、その表面は資材との摩擦や作業員歩行時の作業靴との摩擦によって、毛玉ができたり、比較的短期間のうちに破損する。
【０００４】
この様な摩擦等による不織布表面性状の劣化を抑止し、また施工後に鳥獣等による繊維の引抜を抑止する技術として、本発明者は少なくとも片面に熱可塑性繊維の溶融塊を形成した長繊維を用いた不織布を提案した（特許文献１参照）。
【０００５】
上記長繊維不織布は少なくとも片面に当該繊維の溶融塊を形成することにより、鳥獣等による破壊に対して抵抗性が高く、加えて表面の静止摩擦抵抗（対長靴）が高いなどの改善がなされている。
【０００６】
一方、短繊維からなる不織布は優れた透水性を有することから洗屈防止・吸出防止等の高い透水性が要求される分野に多用されている。しかしながら短繊維不織布は容易に引き抜くことができるため、例えば護岸における土砂吸出し防止シートとして用いると波浪により比較的短時間で破損することがある。また短繊維不織布は耐摩耗性が低く、しかも表面の毛羽ループが多いため、取扱い性が悪いなど、改善の余地が残されていた。
【０００７】
【特許文献１】
特開２００１−１３１８５５号（請求項１等）
【０００８】
【発明が解決しようとする課題】
本発明は上記事情に鑑みてなされたものであって、その目的は高い透水性を有しつつ、耐摩耗性に優れた不織布、及びその製造方法を提供することを目的とする。
【０００９】
【課題を解決するための手段】
上記課題を達成し得た本発明とは、熱可塑性繊維を用いた短繊維不織布の少なくとも片面に、該繊維の溶融塊を有するものであることに要旨を有する短繊維不織布である。
【００１０】
該不織布の溶融塊形成面における該溶融塊の占める面積が１５〜６０％であることが推奨され、該不織布における溶融塊の形成側表面の摩耗級（ＪＩＳ Ｌ１０９６ ８．１７に基づく）が、３級以上であることが望ましい。
【００１１】
上記本発明の不織布を製造するにあたっては、熱可塑性繊維よりなる短繊維を使用し、且つ交絡処理された短繊維不織布の少なくとも片面を、前記熱可塑性繊維の溶融温度よりも３０℃以上高い温度に曝し、繊維の溶融塊を形成することが推奨される。また該片面を火炎に曝して繊維の溶融塊を形成することが推奨される。
【００１２】
【発明の実施の形態】
本発明に係る短繊維不織布は、熱可塑性繊維を用いた短繊維不織布の少なくとも片面に該繊維の溶融塊を有することに要旨を有する。
【００１３】
少なくとも片面に溶融塊を形成した短繊維不織布は優れた透水性と耐摩耗性を兼ね備えている。本発明者らは研究の結果、短繊維不織布の片面或いは両面に溶融塊を形成しても優れた透水性を維持できることを見出した。これは、不織布を短繊維で構成すると繊維間に隙間が生じ、この隙間は繊維溶融塊が形成されても残存するため、優れた透水性を発揮する。しかもこの隙間は溶融塊面積の割合を高めても依然として存在することから、溶融塊の占める割合（面積比率）を高めても優れた透水性は失われない。
【００１４】
また本発明に係る短繊維不織布の耐摩耗性や表面静止摩擦係数は溶融塊の面積比率を高めることによって向上できる。尚、溶融塊の面積比率が高まると砂質土、セメントブロックとの摩擦係数（建技評第９３２２５号「評価書」２．３．８摩擦試験方法による）が減少する。
【００１５】
したがって優れた耐摩耗性と、工業製品として要求される砂質土、セメントブロックとの摩擦係数（規格値０．５以上）を兼ね備えるには不織布の溶融塊形成面における溶融塊の面積比率は好ましくは１５％以上、より好ましくは２０％以上とすることが望ましい。該面積比率が１５％未満の場合、静止摩擦係数が十分に改善されず、作業時の安全性（作業靴に対する滑りやすさ）が不十分となることがある。また耐摩耗性（ＪＩＳ Ｌ１０９６．８．１７に基づいて測定した摩耗級）が３級を下回り、実用性に欠けることがある。特に摩耗級が１級や２級の場合、工事現場などの過酷な環境下で使用すると、資材や作業靴との摩擦によって不織布表面に毛羽が生じて十分な耐摩耗性を発揮できず、また施工後の不織布の風雨、砂等によるやすり効果を受けて容易に繊維の抜け、ほつれを生じ、長期使用目的を達成し得ない。
【００１６】
一方、溶融塊の面積比率を高めると耐摩耗性や表面静止摩擦係数が向上するものの、砂質土、セメントブロックとの摩擦係数が低下して上記規格値を下回り、実用性に欠けることがある。したがって溶融塊の面積比率は好ましくは６０％以下、より好ましくは５０％以下とすることが望ましい。
【００１７】
本発明において透水性とは、不織布の一方面から他方面側への水の透過性をいい、片面に溶融塊が形成された不織布では、該溶融塊形成面から溶融塊非形成面方向への透水性を意味しており、透水係数（ｃｍ／ｓｅｃ）はＪＩＳ Ａ１２１８ ３．１（１）に基づいて測定した値である。
【００１８】
本発明者らの研究によれば、素材、繊維径、繊維長などが同じで、且つ交絡処理を施した短繊維不織布であれば、その片面側に形成される溶融塊の面積比率を増加させても、透水性には殆ど影響しないことを確認している。したがって、所定の透水係数を得るには、用いる短繊維の径や長さ、不織布としての目付けや厚さ、更には交絡処理数などによって適宜調整すればよい。
【００１９】
取扱い性とは、短繊維不織布の敷き広げ容易性、施工作業容易性をいう。取扱い性が低いと設置現場で敷設施工する時の敷き広げが困難となり、或いは不織布同士のまつわりつきが生じて施工作業が困難となる。上記本発明の短繊維不織布は不織布同士の摩擦抵抗（不織布同士の摩擦係数）も低いため、取扱い性にも優れている。また溶融塊形成面には毛羽・ループがほとんど無いことから毛羽やループによる不織布同士のからまりがなく、取扱い性が良好である。尚、不織布の両面に溶融塊を形成すると一段と取扱い性が向上するので望ましい。
【００２０】
本発明では上記溶融塊は不織布の両面に形成してもよい。短繊維不織布であれば両面に溶融塊を形成した場合であっても、該不織布は高い透水性を保持し、しかも不織布両面の耐摩耗性を向上できるので望ましい。不織布の両面に溶融塊を形成すると、一方の面で地面との摩擦に対する耐摩耗性を発揮し、また他方の面では資材や靴との摩擦に対する耐摩耗性を発揮するため、短繊維不織布の耐用期間を一段と延長できる。
【００２１】
以下、本発明の短繊維不織布の製造方法を説明するが、本発明の製造方法を下記方法に限定する趣旨ではなく、公知技術に基づいて適宜変更を加えることもできる。また本発明の短繊維不織布は下記方法によって製造されたものに限定する趣旨ではない。
【００２２】
本発明の短繊維不織布は、加熱よって繊維の一部（または全部）を溶融させて溶融塊を形成するため、ポリエステル、ナイロン、ポリエチレン、ポリプロピレン、ビニリデン、ポリ塩化ビニルなどの各種熱可塑性繊維（短繊維）を用いることが望ましい。尚、短繊維は１種、或いは２種以上を組み合せて不織布としてもよい。また熱可塑性繊維にアクリル繊維を適宜混繊してもよい。アクリル繊維を熱可塑性繊維に混繊すると耐候性が向上するので望ましい。
【００２３】
本発明の不織布の製造方法は特に以下の方法に限定されず、本発明の上記特性を有する不織布が得られる限り、適宜変更してもよい。例えば任意の熱可塑性繊維を単独、又は２種以上組み合せ、更にアクリル繊維を適宜混繊させたものを用いて均一な繊維ウエッブを作成し、得られた繊維ウエッブにニードルパンチ加工やウォータージェット加工などの交絡処理を施して繊維同士を交絡させて不織布とすればよい。交絡処理を施すことによって繊維同士を交絡させれば、不織布としての一体性を高めることができる。尚、ニードルパンチ加工等の交絡処理に伴うニードル数等の交絡数は限定されず、所定の値とすればよい。不織布の厚みを増すと耐突刺強度（突起物に対する不織布の穴の開き難さ）が向上すると共に、石などの突起物や地面の凹凸にも柔軟に適合し、不織布の破損を抑制することができる。尚、短繊維不織布の厚さは用途に応じて適宜変更すればよい。
【００２４】
短繊維不織布の少なくとも片面に溶融塊を形成する方法としては、例えば該不織布の少なくとも片面を加熱し、熱可塑性繊維を溶融させて溶融塊を形成すればよい。また不織布の両面を加熱処理すると、両面に溶融塊を形成できる。勿論、片面を加熱して溶融塊を形成した後に、更に他の面を加熱して溶融塊を形成してもよい。溶融塊を有する短繊維不織布を効率的に製造するには、該不織布の製造工程に該不織布の加熱工程を設けることが望ましい。
【００２５】
例えば短繊維から成る繊維層をそのまま、或いは複数枚重ねて積層した後、該繊維層或いは積層体をニードルパンチ加工などによって一体化処理して不織布を形成した後、毛焼処理やカレンダー加工などの表面加熱機を利用し、不織布表面付近の熱可塑性繊維を加熱溶融させれば溶融塊を形成できる。
【００２６】
尚、加熱方法としては上記の様な表面処理に用いる装置に限らず、ガスバーナーなどの火炎を利用しても良い。火炎を利用すると短時間で容易に溶融塊を形成できるので望ましい。不織布を火炎（溶融温度の１５０℃以上の温度）に曝すと、熱可塑性繊維が溶融し、短繊維同士が融着すると共に、不織布表面に細かな溶融塊の凹凸が形成され、該凹凸も不織布の一体性向上に寄与するため、不織布の一体性向上に寄与するだけでなく、該凹凸は繊維同士の摩擦係数の低下にも寄与するので望ましい。
【００２７】
この際の溶融状態や溶融深さは、加熱温度、加熱速度、熱源からの距離などをコントロールすることによって調節できる。
【００２８】
溶融塊を形成するには、加熱温度を熱可塑性繊維の溶融温度よりも好ましくは３０℃以上、より好ましくは５０℃以上、更に好ましくは１００℃以上、最も好ましくは１５０℃以上とすることが望ましい。また加熱温度を調整することによって、同じ加熱速度を採用した場合であっても不織布表面に形成される溶融塊の面積比率を調整できる。
【００２９】
加熱工程における不織布の加熱時間は短時間であることが望ましい。加熱時間が長くなると、不織布の内部まで溶融してしまい、短繊維自体の弾力性や耐折損性などの強度が急激に劣化してしまい、不織布に荷重を付加した際に不織布が割れたり、剪断応力を加えた際に不織布が破れ易くなる。
【００３０】
特に不織布を火炎に曝す場合、短時間で不織布の内部まで溶融してしまう恐れがあるので、不織布表面付近のみを溶融させるには、適宜ガス圧や不織布の移動速度などを適正に調整することが望ましい。例えばガス圧１００ｋｇ／ｃｍ2以上の場合、処理（移動）速度を１１ｍ／ｍｉｎ未満とすることが望ましい。
【００３１】
本発明の製造方法によれば複雑な処理工程を要することなく溶融塊を有する短繊維不織布を製造できるため、生産性に優れている。
【００３２】
以下、本発明を実施例に基づいて説明するが、本発明の不織布は下記実施例に限定されるものではない。
【００３３】
【実施例】
実施例に用いた各試料を下記の方法で製造した。
【００３４】
試料Ｎｏ．１
平均繊度１６．７デシテックス(dtex)、繊維長６４ｍｍのポリエチレンテレフタレート繊維の再生綿３０質量％と、平均繊度６．６デシテックス、繊維長６４ｍｍのポリエチレンテレフタレート繊維の再生綿４０質量％と、平均繊度６．６デシテックス、繊維長６４ｍｍのポリエチレンテレフタレート繊維の黒原着３０質量％からなる繊維層をニードルパンチ加工（針深度８ｍｍ、打込み本数９０本／ｃｍ2）を施し、目付１２００ｇ／ｍ2、厚さ８ｍｍの不織布を得た。該不織布の片面をガス毛焼加工して本発明の短繊維不織布を得た。尚、ガス毛焼加工には、直火バーナーを火炎が下斜め４５度になる様に配置して、火炎長は該バーナーの火炎孔から約５ｃｍの火炎となる様に調整した。ガス圧は１００ｋｇ／ｃｍ2とした。また該火炎孔から２ｃｍの距離に上記不織布を配置し、処理速度１０ｍ／ｍｉｎで不織布を火炎に曝した。直火バーナーは上記不織布の幅方向にピッチ３ｍｍの火炎孔３列、列間隔３ｍｍの千鳥配置とした。
【００３５】
試料Ｎｏ．２
ガス毛焼加工時の処理速度を７．５ｍ／ｍｉｎとした以外は試料Ｎｏ．１と同様にして短繊維不織布を得た。
【００３６】
試料Ｎｏ．３
上記試料Ｎｏ．２で得た短繊維不織布２の裏面（加熱処理していない面）に試料Ｎｏ．２と同様のガス毛焼加工を施して短繊維不織布を得た。
【００３７】
試料Ｎｏ．４
ガス毛焼加工時の処理速度を６ｍ／ｍｉｎとした以外は試料Ｎｏ．１と同様にして短繊維不織布を得た。
【００３８】
試料Ｎｏ．５
ガス毛焼加工を施さなかった以外は試料Ｎｏ．１と同様にして短繊維不織布を得た。
【００３９】
試料Ｎｏ．６
ガス毛焼加工時の処理速度を１１．０ｍ／ｍｉｎとした以外は試料Ｎｏ．１と同様にして短繊維不織布を得た。
【００４０】
上記各試料を以下の評価基準に基づいて評価した。
【００４１】
単位面積あたりの質量（目付量）；
ＪＩＳ Ｌ１０９６ ８．４に記載されている方法に基づいて質量を測定した。
【００４２】
厚さ；
ＪＩＳ Ｌ１０９６ ８．５に基づいて荷重２ＫＰａで厚みを測定した。
【００４３】
耐摩耗性評価；
ＪＩＳ Ｌ１０９６ ８．１７に基づいてテーバ型摩耗試験機で測定した。
【００４４】
透水係数；
ＪＩＳ Ａ１２１８ ３．１（１）に基づいて透水係数を測定した。
【００４５】
表面摩擦係数；
建技評第９３２２５号「評価書」２．３．８摩擦試験方法に基づいて静止摩擦係数を測定した。摩擦係数μ１，μ２，μｐは以下の係数を示す。
μ１：堤体土（砂質土）と不織布の摩擦係数
μ２：セメントブロックと不織布の摩擦係数
μｐ：不織布同士の摩擦係数
【００４６】
表面の静止摩擦係数；
試料を十分に濡らして水平台上に配置し、砂５ｋｇを詰めたゴム長靴（月星社製）を該試料に載置して該台を傾斜させ、該長靴が滑った時点における該台の傾斜角度を測定し、該角度の正接を表面の静止摩擦係数とした。
【００４７】
表面積当りの溶融塊の面積比率；
試料表面をマイクロスコープ（株式会社キーエンス社製）によって２５倍に拡大し、実長さ１ｃｍ角の範囲の溶融塊の面積を切出し紙質量で測定し、全体質量に対して溶融塊の質量比により下記式に基づいて溶融塊の面積比率を求めた。
表面積当りの溶融塊の面積比率＝（溶融塊の紙質量／１ｃｍ2当りの紙質量）×１００（％）
取扱性；
試料（２ｍ×２０ｍ）の取扱い性は、各試料を設置現場で敷設施工する際の敷き広げ時の容易性（不織布同士のまつわりつき）及び施工時における容易性（もも毛、ループなどの発生による施工阻害性）について評価した。
【００４８】
◎：敷き広げ及び施工が極めて容易であり、特に優れている。
○：敷き広げ及び施工が容易。
△：敷き広げ、および／または施工にやや難がある。
×：敷き広げ、および／または施工が困難。
【００４９】
不織布表面の毛羽・ループの状態；
試料表面（溶融塊形成面）における毛羽・ループの有無を目視で確認した。
【００５０】
結果を表１に示す。
【００５１】
【表１】
【発明の効果】
本発明の上記短繊維不織布は、少なくとも片面に溶融塊を形成することによって高い透水性を有しつつ、優れた耐摩耗性を有する。また短繊維不織布を用いることで、長繊維不織布に比べて容易に不織布の厚みを増すことができ、優れた耐突刺性を簡易な製造方法で得ることができる。更に溶融度合を調整することで耐摩耗性に優れた短繊維不織布を提供できる。特に短繊維不織布の両面に溶融塊を形成すると、両面の耐摩耗性が高められ、作業時の短繊維同士や地面との摩擦による毛羽立ちが抑制されて、優れた取扱性を有する他、安定して高レベルの透水性を持続する。
【００５３】
本発明の上記短繊維不織布を製造する方法によれば、簡易な方法で透水性と耐摩耗性等に優れた短繊維不織布を提供できるので、生産性（生産コストが安い）に優れている。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a short-fiber nonwoven fabric used as a suction-prevention sheet, an uneven settlement-prevention sheet, a protection sheet, and the like in an environment exposed to the outdoors for a long period of time, such as a seawall, soft ground, and a final waste disposal site, and a method for producing the same It is about.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various types of nonwoven fabrics have been used as civil engineering sheets in civil engineering sites for the purpose of preventing unequal settlement in soft ground and preventing buckling and suction in rivers and coasts.
[0003]
Since the nonwoven fabric used in these applications is used outdoors, its surface can be pilled or broken in a relatively short time due to friction with materials and friction with work shoes when workers walk. .
[0004]
As a technique for suppressing the deterioration of the surface properties of the nonwoven fabric due to such friction and the like, and for preventing the fiber from being pulled out by a bird or the like after construction, the present inventor has used a long fiber having a molten mass of thermoplastic fiber formed on at least one surface. A nonwoven fabric was proposed (see Patent Document 1).
[0005]
By forming a molten mass of the fiber on at least one side, the long-fiber nonwoven fabric has high resistance to destruction by birds and beasts and the like, and in addition, has improved surface static friction resistance (anti-boots) and the like. I have.
[0006]
On the other hand, nonwoven fabrics made of short fibers have excellent water permeability, and are therefore frequently used in fields requiring high water permeability such as prevention of buckling and suction. However, since the short-fiber nonwoven fabric can be easily pulled out, if it is used as, for example, a sheet for preventing earth and sand from being sucked in a seawall, it may be damaged in a relatively short time by waves. In addition, short fiber nonwoven fabrics have low abrasion resistance and have many fluff loops on the surface, so that there is room for improvement such as poor handling properties.
[0007]
[Patent Document 1]
JP-A-2001-131855 (Claim 1 etc.)
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a nonwoven fabric having high water permeability and excellent wear resistance, and a method for producing the same.
[0009]
[Means for Solving the Problems]
The present invention that has achieved the above object is a short-fiber nonwoven fabric that has a gist that at least one surface of a short-fiber nonwoven fabric using a thermoplastic fiber has a molten mass of the fiber.
[0010]
It is recommended that the area occupied by the molten mass on the molten mass forming surface of the nonwoven fabric is 15 to 60%, and the abrasion class (based on JIS L1096 8.17) of the surface of the nonwoven fabric on the forming side of the molten mass is 3 It is desirable that the class be equal to or higher.
[0011]
In producing the nonwoven fabric of the present invention, a short fiber made of a thermoplastic fiber is used, and at least one surface of the entangled short fiber nonwoven fabric is heated to a temperature higher by 30 ° C. or more than the melting temperature of the thermoplastic fiber. Exposure to form a molten mass of fiber is recommended. It is also recommended that the one side be exposed to a flame to form a molten mass of fibers.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The short fiber nonwoven fabric according to the present invention has a gist that at least one surface of the short fiber nonwoven fabric using a thermoplastic fiber has a molten mass of the fiber.
[0013]
The short-fiber nonwoven fabric having a molten mass formed on at least one side has both excellent water permeability and abrasion resistance. As a result of research, the present inventors have found that excellent water permeability can be maintained even when a molten mass is formed on one or both surfaces of a short fiber nonwoven fabric. This is because, when the nonwoven fabric is composed of short fibers, gaps are formed between the fibers, and the gaps remain even if a molten fiber mass is formed, thereby exhibiting excellent water permeability. Moreover, since these gaps are still present even when the area ratio of the molten mass is increased, excellent water permeability is not lost even if the ratio (area ratio) occupied by the molten mass is increased.
[0014]
Further, the wear resistance and the coefficient of surface static friction of the short fiber nonwoven fabric according to the present invention can be improved by increasing the area ratio of the molten mass. When the area ratio of the molten mass increases, the coefficient of friction with the sandy soil and the cement block (according to the construction test No. 93225 “Evaluation Report” 2.3.8 friction test method) decreases.
[0015]
Therefore, in order to combine excellent abrasion resistance with the coefficient of friction (standard value 0.5 or more) with sandy soil and cement blocks required for industrial products, the area ratio of the molten mass on the molten mass forming surface of the nonwoven fabric is preferable. Is preferably at least 15%, more preferably at least 20%. When the area ratio is less than 15%, the coefficient of static friction is not sufficiently improved, and safety during work (slipperiness with respect to work shoes) may be insufficient. Further, the wear resistance (wear class measured based on JIS L1096.8.17) is lower than class 3 and may be lacking in practicality. Especially when the wear grade is 1st or 2nd grade, when used in a severe environment such as a construction site, the friction with materials and work shoes causes fuzz on the surface of the nonwoven fabric, so that sufficient abrasion resistance cannot be exhibited. Due to the rasp effect of the nonwoven fabric after construction due to wind, rain, sand, etc., the fibers easily come off or fray, and the long-term use purpose cannot be achieved.
[0016]
On the other hand, when the area ratio of the molten mass is increased, the wear resistance and the coefficient of static friction on the surface are improved, but the coefficient of friction with the sandy soil and the cement block is lower than the above-mentioned standard value, which may be lacking in practicality. . Therefore, the area ratio of the molten mass is preferably set to 60% or less, more preferably 50% or less.
[0017]
In the present invention, the water permeability refers to the permeability of water from one surface of the nonwoven fabric to the other surface, and in a nonwoven fabric in which a molten mass is formed on one surface, the direction of the molten mass from the surface on which the molten mass is not formed to the surface on which the molten mass is not formed. It means water permeability, and the water permeability coefficient (cm / sec) is a value measured based on JIS A1218 3.1 (1).
[0018]
According to the study of the present inventors, the raw material, fiber diameter, fiber length and the like are the same, and if it is a short fiber nonwoven fabric subjected to entanglement treatment, the area ratio of the molten mass formed on one side thereof is increased. However, it has been confirmed that it hardly affects the water permeability. Therefore, in order to obtain a predetermined water permeability, the diameter and length of the short fibers used, the basis weight and thickness as a nonwoven fabric, and the number of entangled treatments may be appropriately adjusted.
[0019]
The handleability refers to the ease of spreading the short fiber nonwoven fabric and the ease of construction work. If the handling property is low, it is difficult to spread the laying work at the installation site, or the nonwoven fabrics are wrapped around each other and the working work is difficult. The short-fiber nonwoven fabric of the present invention has a low frictional resistance between nonwoven fabrics (a coefficient of friction between nonwoven fabrics) and is therefore excellent in handleability. Further, since there is almost no fluff or loop on the surface where the molten mass is formed, the nonwoven fabric is not entangled by the fluff or loop, and the handleability is good. In addition, it is desirable to form a molten mass on both sides of the nonwoven fabric because the handleability is further improved.
[0020]
In the present invention, the molten mass may be formed on both sides of the nonwoven fabric. A short-fiber nonwoven fabric is desirable because it retains high water permeability and can improve the abrasion resistance of both sides of the nonwoven fabric even when a molten mass is formed on both sides. If a molten mass is formed on both sides of the nonwoven fabric, one side will exhibit abrasion resistance against friction with the ground and the other side will exhibit abrasion resistance against friction with materials and shoes. The service life can be further extended.
[0021]
Hereinafter, the method for producing the short-fiber nonwoven fabric of the present invention will be described. However, the present invention is not limited to the following method, and may be appropriately modified based on a known technique. The short fiber nonwoven fabric of the present invention is not intended to be limited to those manufactured by the following method.
[0022]
Since the short fiber nonwoven fabric of the present invention melts a part (or all) of the fiber by heating to form a molten mass, various thermoplastic fibers such as polyester, nylon, polyethylene, polypropylene, vinylidene and polyvinyl chloride (short fiber) are used. It is desirable to use fibers. The short fibers may be used alone or in combination of two or more to form a nonwoven fabric. In addition, acrylic fibers may be appropriately mixed with thermoplastic fibers. It is desirable to mix the acrylic fiber with the thermoplastic fiber because the weather resistance is improved.
[0023]
The method for producing the nonwoven fabric of the present invention is not particularly limited to the following method, and may be appropriately changed as long as the nonwoven fabric having the above characteristics of the present invention is obtained. For example, any thermoplastic fiber may be used alone or in combination of two or more types, and a uniform fiber web may be prepared using a mixture of acrylic fibers as appropriate, and the obtained fiber web may be subjected to needle punching, water jet processing, or the like. The fibers may be entangled with each other to form a nonwoven fabric. If the fibers are entangled by performing the entanglement treatment, the integrity of the nonwoven fabric can be enhanced. Note that the number of confounds such as the number of needles involved in confounding processing such as needle punching is not limited, and may be a predetermined value. Increasing the thickness of the non-woven fabric improves the puncture resistance (the difficulty of opening the non-woven fabric's holes with respect to the protrusions), and also flexibly adapts to protrusions such as stones and irregularities on the ground, thereby suppressing breakage of the non-woven fabric. it can. Incidentally, the thickness of the short fiber nonwoven fabric may be appropriately changed according to the application.
[0024]
As a method of forming a molten mass on at least one surface of the short fiber nonwoven fabric, for example, at least one surface of the nonwoven fabric may be heated to melt thermoplastic fibers to form a molten mass. When both sides of the nonwoven fabric are heat-treated, a molten mass can be formed on both sides. Of course, after one surface is heated to form a molten mass, the other surface may be further heated to form a molten mass. In order to efficiently manufacture a short-fiber nonwoven fabric having a molten mass, it is desirable to provide a heating process for the nonwoven fabric in the nonwoven fabric manufacturing process.
[0025]
For example, a fiber layer composed of short fibers as it is or after a plurality of layers are laminated and laminated, the fiber layer or the laminated body is integrated by a needle punching process or the like to form a nonwoven fabric, and then subjected to a hair-burning process or a calendering process. When a thermoplastic fiber near the surface of the nonwoven fabric is heated and melted using a surface heater, a molten mass can be formed.
[0026]
The heating method is not limited to the apparatus used for the surface treatment as described above, and a flame such as a gas burner may be used. It is desirable to use a flame because a molten mass can be easily formed in a short time. When the nonwoven fabric is exposed to a flame (a melting temperature of 150 ° C. or higher), the thermoplastic fibers are melted, the short fibers are fused together, and fine irregularities of a molten mass are formed on the surface of the nonwoven fabric. In addition to contributing to the improvement of the integrity of the nonwoven fabric, the unevenness is desirable because it also contributes to the reduction of the coefficient of friction between the fibers.
[0027]
The melting state and the melting depth at this time can be adjusted by controlling the heating temperature, the heating rate, the distance from the heat source, and the like.
[0028]
In order to form a molten mass, the heating temperature is preferably 30 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 100 ° C. or higher, and most preferably 150 ° C. or higher than the melting temperature of the thermoplastic fiber. . Further, by adjusting the heating temperature, the area ratio of the molten mass formed on the nonwoven fabric surface can be adjusted even when the same heating rate is employed.
[0029]
The heating time of the nonwoven fabric in the heating step is desirably short. If the heating time is long, the inside of the nonwoven fabric will be melted, and the strength of the short fiber itself, such as elasticity and breakage resistance, will be rapidly deteriorated.When a load is applied to the nonwoven fabric, the nonwoven fabric will break or shear. When stress is applied, the nonwoven fabric is easily broken.
[0030]
In particular, when exposing the nonwoven fabric to a flame, the inside of the nonwoven fabric may be melted in a short time.Therefore, in order to melt only the vicinity of the nonwoven fabric surface, the gas pressure and the moving speed of the nonwoven fabric need to be appropriately adjusted. desirable. For example, when the gas pressure is 100 kg / cm 2 or more, it is desirable to set the processing (moving) speed to less than 11 m / min.
[0031]
According to the production method of the present invention, a short-fiber nonwoven fabric having a molten mass can be produced without requiring a complicated processing step, so that the productivity is excellent.
[0032]
Hereinafter, the present invention will be described based on examples, but the nonwoven fabric of the present invention is not limited to the following examples.
[0033]
【Example】
Each sample used in the examples was manufactured by the following method.
[0034]
Sample No. 1
30% by mass of recycled cotton made of polyethylene terephthalate fiber having an average fineness of 16.7 dtex and a fiber length of 64 mm, and 40% by mass of recycled cotton made of polyethylene terephthalate fiber having an average fineness of 6.6 decitex and a fiber length of 64 mm. A fiber layer consisting of 30% by mass of black terephthalate fiber having a fiber length of 64 mm and a fiber length of 64 decitex was subjected to needle punching (needle depth: 8 mm, number of punches: 90 / cm 2 ), and the basis weight was 1200 g / m 2 and the thickness was 8 mm. Was obtained. One side of the non-woven fabric was subjected to gas hair baking to obtain the short-fiber non-woven fabric of the present invention. In addition, in the gas-burning process, a direct-fired burner was arranged so that the flame was obliquely at an angle of 45 degrees downward, and the flame length was adjusted so that the flame was about 5 cm from the flame hole of the burner. The gas pressure was 100 kg / cm 2 . The nonwoven fabric was placed at a distance of 2 cm from the flame holes, and the nonwoven fabric was exposed to a flame at a processing speed of 10 m / min. The direct fire burners were arranged in three rows of flame holes with a pitch of 3 mm in the width direction of the nonwoven fabric and in a staggered arrangement with a line interval of 3 mm.
[0035]
Sample No. 2
Sample No. was obtained except that the processing speed during the gas sintering was 7.5 m / min. In the same manner as in Example 1, a short fiber nonwoven fabric was obtained.
[0036]
Sample No. 3
The above sample No. Sample No. was placed on the back surface (the surface not subjected to heat treatment) of the short fiber nonwoven fabric 2 obtained in Step 2. Gas sintering was performed in the same manner as in Example 2 to obtain a short-fiber nonwoven fabric.
[0037]
Sample No. 4
Sample No. was obtained except that the processing speed during the gas briquetting was 6 m / min. In the same manner as in Example 1, a short fiber nonwoven fabric was obtained.
[0038]
Sample No. 5
Sample No. 2 was not subjected to gas briquetting. In the same manner as in Example 1, a short fiber nonwoven fabric was obtained.
[0039]
Sample No. 6
Sample No. was obtained except that the processing speed during the gas briquetting process was set to 11.0 m / min. In the same manner as in Example 1, a short fiber nonwoven fabric was obtained.
[0040]
Each of the samples was evaluated based on the following evaluation criteria.
[0041]
Mass per unit area (basis weight);
The mass was measured based on the method described in JIS L1096 8.4.
[0042]
thickness;
The thickness was measured at a load of 2 KPa based on JIS L1096 8.5.
[0043]
Abrasion resistance evaluation;
It was measured with a Taber abrasion tester based on JIS L1096 8.17.
[0044]
Hydraulic conductivity;
The water permeability was measured based on JIS A1218 3.1 (1).
[0045]
Surface friction coefficient;
The coefficient of static friction was measured based on the construction test No. 93225 “Evaluation Report” 2.3.8 Friction test method. The friction coefficients μ1, μ2, and μp indicate the following coefficients.
μ1: Friction coefficient between embankment soil (sandy soil) and nonwoven fabric μ2: Friction coefficient between cement block and nonwoven fabric μp: Friction coefficient between nonwoven fabrics
Coefficient of static friction of the surface;
The sample was sufficiently wetted and placed on a horizontal platform, and rubber boots (manufactured by Tsukisei) filled with 5 kg of sand were placed on the sample, the platform was inclined, and the platform was slid when the boots slid. The inclination angle was measured, and the tangent of the angle was defined as the coefficient of static friction of the surface.
[0047]
Area ratio of molten mass per surface area;
The sample surface was magnified 25 times with a microscope (manufactured by Keyence Corporation), the area of the molten mass in the range of the actual length of 1 cm square was measured by cutting paper mass, and the mass ratio of the molten mass to the total mass was determined. The area ratio of the molten mass was determined based on the following equation.
Area ratio of molten mass per surface area = (paper mass of molten mass / paper mass per 1 cm 2 ) x 100 (%)
Handleability;
The ease of handling of samples (2m x 20m) depends on the ease of spreading (wrapping between nonwoven fabrics) when laying each sample at the installation site and the ease of construction (thigh hair, loops, etc. (Inhibition of construction).
[0048]
A: Spreading and construction are extremely easy and particularly excellent.
：: Easy spread and construction.
Δ: There is some difficulty in spreading and / or construction.
×: Difficult to spread and / or construct.
[0049]
Fluff and loop on the surface of the nonwoven fabric;
The presence or absence of fluff and loops on the sample surface (the surface on which the molten mass was formed) was visually confirmed.
[0050]
Table 1 shows the results.
[0051]
[Table 1]
【The invention's effect】
The short fiber nonwoven fabric of the present invention has high abrasion resistance while having high water permeability by forming a molten mass on at least one surface. Further, by using the short-fiber nonwoven fabric, the thickness of the nonwoven fabric can be easily increased as compared with the long-fiber nonwoven fabric, and excellent puncture resistance can be obtained by a simple manufacturing method. Further, by adjusting the degree of melting, a short-fiber nonwoven fabric having excellent wear resistance can be provided. In particular, when a molten mass is formed on both sides of the short-fiber nonwoven fabric, the abrasion resistance of both sides is enhanced, the fuzzing due to friction between the short fibers during work and the ground is suppressed, and in addition to having excellent handling properties, stable To maintain a high level of water permeability.
[0053]
According to the method for producing a short-fiber nonwoven fabric of the present invention, a short-fiber nonwoven fabric having excellent water permeability and abrasion resistance can be provided by a simple method, so that the productivity (the production cost is low) is excellent.
Claims (5)
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2008002009A (en) * | 2006-06-22 | 2008-01-10 | Kureha Ltd | Backing for floor mat and method for producing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008002009A (en) * | 2006-06-22 | 2008-01-10 | Kureha Ltd | Backing for floor mat and method for producing the same |
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